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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f31014c82aa5ea8878f42ccdd70b3c435632b19bdf6c7e643bf1d7005dcde3c' 
  AND token = 'evoSOiZzmKFmDsvvcF6PISKLK7Ochl5K1nW9Lv+SVrE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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