SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b1fd58b261b9d28cb436e235d9d27a8c094a91a9117524874866c85889dd471' 
  AND token = 'zdVNIBMY2V6+B7v16ypbbL+jskvsHYJVTSxHYUCPelE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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