SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db9ee78ef762cd0307377c21c36873514c2051cddb218644c92147f87c56b8a5' 
  AND token = 'eRMfIZz3XYkzeUb6/YxzbK3XkQoJQLWY8FZXGMGADmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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