SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c84c627ce2347cd2aeb02374d6bbb922fecb9c52006eb77fdb80fff586698e40' 
  AND token = 't7EugNBFZWbTeiCUF6uKA7MPPlw7nuPNl0v2RTwaVq0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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