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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd83e7b8674fa2d987be21105d20bbb4b00a29aebfefe37ee51d2b07ca6aa3e05' 
  AND token = 'PfMPUiY+FpvlAZYnGzzURYX9gnF7mOAstlyf6gOaQNQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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