SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd94683cd0157725a31ddfcee91742aceb8f9416237b76f23b19394416d3ddc1d' 
  AND token = 'Eg+vtUtIyp6aHAXqt1pvWz4DA1m89+agDIQGRDDVvb4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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