SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e57fc15a71abf38378f96ce2b0f269826e05c4c17d4ace53017d5a8c46bb4ae' 
  AND token = 'R5n7zUiGrH9x/q5TYgwL1zkkLAwGVU8Ue8E+OKZHjR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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