SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c553c17d81bf4233c1cc0b8a48b4a79cc57ce7378f1f9538386ef410ccef395a' 
  AND token = 'VnDgC+x+dS0dtNSnsJiGCS2nOD7PeKJALMEsxdRoONY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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