SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '798f6e97e960095a7ce04b4dfdcfd04d39f1208dc39e8b84021886d9549842dc' 
  AND token = '7BCS7qNxu/P+3biUwSRXJySZ8xVuNuG37hXug7+YCRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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