SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e91edf8b834af2f080e6a7e715bb2cb3c311457cabac3cb8ada7eeb88911705' 
  AND token = 'kwwh4BJL1B3DUV3wtuT8xBwFRnm4+jQdHMmDQcbkpy8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}