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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '64d9767974df3f22cfd2dcc9c9bf8bf4b513eb5d1c3f48b4c84c7c971e0c24bc' 
  AND token = 'Xn1V5T/CN1Trs0Qc0Pdc6L2oRreAf+Hnv+wSZN6libQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}