SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9803cf234d9cfeb4431ffafb180d70a6a54717729e843986e6de0fdfc8ade85' 
  AND token = 'sKuBBgeThRMBJOuvNGk/8meeY7nynpwkXfNzhACS2PY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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