SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f0dd3c41ac21dc2c2a825bc218cb1c07b4b93a5f7c6601849447f4b8a07c7d63' 
  AND token = 'WiZU8Tm8IFHsAVZGiAmu51fkhgpGL2xnI25LZBfkuEU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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