SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28bbd9216f9e708d721d9ed663fdfaf4f5aff29b111456f0a9e78292d33d8542' 
  AND token = '7P5+3E5LwmNu1IUsOxPFvvG7qn2N+XoVAKgfY+yU1w8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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