SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28ada753a0d258dd76c91d6c01fd691fde8910e903b0dd379a227ad8a483d8e8' 
  AND token = 'xilIppFvMF+VFzlsv3+AQajUVP51anSoo7/LASR08JI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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