SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'e400dec307a7d1f24a3c40ae61bc882d64ef66e6d0155a7747f7c85b23d9ea3b' 
  AND token = 'JUuCwlPgBY5P8z3RmOiYfyzC/z/KnHsHaXRsW2qocx4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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