SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c62f9caaa5cf5e2c78add1bcb3c27c6f0211674ed4be49635f1b6aa5e878be5' 
  AND token = 'hE1xFoJ91HwDazYoduqsZlbkeTrndm5a/JnIImoCnMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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