SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5c821db982612b0bafcd641999423781a41c67daf7d32f8f778525fb6ea4f2c' 
  AND token = 'eB2VWdsw8HjSTJX//EEGz4YaKs6VUi/xhE2ILpTVlZg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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