SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5b914b30ef33d842bd774d0561abdb2c1129857f575158b57972e72eb52c9614' 
  AND token = 'dsgaJpPJ3tuSUChbmaHH8SAVqsYfPIJNo2FCgGettfM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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