SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5db197316368ad4383cde1645871cf0bc1557c8ff4f8826381eda60d81162e8' 
  AND token = 'XZ20yvFi4uOo11rkgRt+vboPulxFeuXoUoAuXf6rs0g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}