SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '779d0cacc80e2f06666d4e12bc835e7d771f40f549b16334f6f53638044427d6' 
  AND token = '5q/PzeIxwXHXxgA+ayT1kke2O6xcKEHfj6yuJZJcdR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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