SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eef64ebc0b6ac7b5d7d7c2d0b502425a2ccc91b988511aac9dea96fd30da63af' 
  AND token = 'ehPTNn/IcdRReEmVZADFWOAqUHwZCwPOpijpuAG/ZVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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