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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7eca4b3b3054361d20c973c3455a32b779af1c0b704dfcb8622ce881e44dac4f' 
  AND token = 'i4ZMOHyicC8/WfxE1bVg6oI6+zAnPCBSioZ+qKPYSbQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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