SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fae203581446ad6bbbfdce16555aeeec4b4e51b25aeb816e270d6e0ec458967' 
  AND token = 'BFrSMn/d9heLhb3pj0FKnnYmrQnIjnSf78A9buXFy50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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