SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7a48ef5f1f6be3652d4b66226e8b2b3e80bb9687044e4d2e63afb65fa75c340' 
  AND token = 'pEARBjplF3JDDqCLyxpzUFXzaXVDmHKMZu6x/vy4BHw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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