SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3fda4dac5b82dd5ef3382828879f07765f35490f78da53b063a7f762645a23fc' 
  AND token = 'qvDKS4slauUFEA0EeNlpRtWNiX7mhGwaLDBqBlihQ8A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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