SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '64df1d1831de3643dafed8edda5b4f0b78eecc7091fb6f3d299aa1471574aedc' 
  AND token = 'hLOzJvIKTnVNxfiuXXT4qDp2/sQg3ry9VTWnN+UlduA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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