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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '277ec8a651fb3c953758136271b46dbc7d6d19caa9dac390a0a0e4755dc16b60' 
  AND token = '8lW9Q+2a6Pqc9fnRI7DIQ2RLz8ZYl/pcQdIDU+2vvTc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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