SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0371d1c100b3ab77f11f96d6b37fe2a76429afd935139e02b324f5ac83f8b639' 
  AND token = 'nPBSIYRqgctrMYdk6dwtz+xZTHIKIWLQfyTnik8UDG8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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