SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79090ac6e688c4498a6e47ba2ed3cff742afd501e4687b981f093272bcca95ad' 
  AND token = '5xD2/LDz2Oq4zFGefPh03vUMRiJNIlS9NqVKpmtVXh4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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