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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'abf8f3cebaad364d92474d9a529dd0228468ad0e2bb99e734886f2eed66e7d74' 
  AND token = 'wEF0hXwm1c2cM9lk+8EYHZRgISXLNVFa1AQfE0eeZ3c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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