SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bb185094cc6b460f9b3daf211465f9f4d589a6eec9ca0ce6deabc6e8c63275c' 
  AND token = 'kP3dP3BbBoE5AwZRobH+xqbdEzIsESP2corMk9KHglM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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