SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c3da7be6a4695fe853c157f2cdf276828f485bb380cdad83c6b351161d1315d' 
  AND token = 'FeaGToMOYKKasKYtHMN5Idheanm40WbwtIPP9MtNYPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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