SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12de1b0f9abec4897b7fafee3a8445b0284ed5c695f0ed69656b5c975de7239c' 
  AND token = '916bh9dtf9hNNINsZ9aIFSOLqRk3q0RHLrYqv9L+VSs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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