SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f67da2ffef3adf38c9efec4fecf408c57a27b6f67917827b51a2aca7776dee6f' 
  AND token = 'vrSunmwfJGF8kgcavGzyQaHEay+cr08jxOh2O908NEE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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