SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1795b0b174cf1c59dd64b8d41e70e3f0cafaff916eb21628b66d7c08c9d1afc' 
  AND token = 'S71c3cD4cbcq6UFQMP8CIPv8Z/W/h6Fr5N6n8LewngM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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