SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5830636fd68131eec1836753cf2652c5ac55307f0199972ec3e6059d84b7647' 
  AND token = 'XGfJvBwJQMiUhIlgQ3bLrFvcLRq3M/s9BXCYL+JbmfY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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