SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40e16fae517d3f09e7aaecda3e71677449bc85838832e77a044d285fd3475451' 
  AND token = '3VSNo0zhoze47ZqsAP/apjH4sMh74dUWSSElKKiYNmE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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