SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8794fffbd93eae1d8fcdecb6d881f76fc63ed671c40dfad84277a9ec3300438' 
  AND token = 'ImS2S6zEJK3FBiRjK/Ui/vVMTtpz+RLJGJDXfKqipSA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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