SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37e3cec1c285213e339a7f5019e8fa994d253536008035436578adcf410597ed' 
  AND token = 'mDztayuqeXfT5JWgI0zfynIj9IGaUdHldodxMUrpVY4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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