SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb51debd96b51810f5f1688978f4a55c2d181adbc1f336d04c5cf6eb0125cd5c' 
  AND token = 'aVFPhVSvsZHNvA4OUDdajiQePI5Uk5pd7NtbzZH2Otg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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