SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c83672d185bfc163aa00a52861e14420663064a826a778ace835e2d8470523f' 
  AND token = 'XT5wG3Wm46pO0r+0hNUwP0nNeDZeV+LjU2nHPv0mOQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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