SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50bea9964d8d295ba2adb327c63ef3156327a1f0ae966b0cadbd13b486e03403' 
  AND token = 'YIAtTBPZWrORF9GdbIbGrlbioxBB7BbjRzbWdc+rauM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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