SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ef10226f8cfd3f4c9ca09dc05753daf3d4eb79f27bd9fc015beba0835dfd4c4' 
  AND token = 'L7PHUIUuD/u81HGAIFf1vLpoOc8Ft4phcPkzWB6nSKc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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