SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c426f364013c9d4d09d246036f745d7fabb82a5634b1e9bc4086ff4903c5edaf' 
  AND token = 'uYYJLZhjnWhzoPjmDmxhTz9B2xmT3/PmxtKyddLVA24=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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