SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b7b2a2fa911b3707d95d5be2df6fa7c8447f5a21844a3a64ecffd4caf307882' 
  AND token = '/99+Gin/Fk3MkWGBRaQsq7UJF64JKAjaip3WTPFCK+Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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