SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '535e4f208df1eafc2ae1610d1262d0fd1f079926bc9823bedb99f51fa30626db' 
  AND token = '/9LDmIrfpjuj3s8uz1zxwrwMFAEUoZClJJ7BABx1FMM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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