SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef46d98705c609e2cfff932750b5b1de9bb4cc1616a7f2dc22f5704148af2d92' 
  AND token = 'I2qLdS3DoAOV1XJyijoTJq50+OSznQAeZUeBdt2NDxY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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