SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d1b4438b84df5baba689895309032f3abf2c98e45ec6c9b0ef27707709d8aa4' 
  AND token = 'TCQcNMmXDGO2kblhqqY9WOh2K/29NOBRmkeIpoA/1Qs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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