SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d5bebcad816dc5cd57937e0865b244480e7a1a1f0c344e0360bb0c1e4fa1509' 
  AND token = 'tUQHtV0nQLGqQhTEmdHKst7PXc79hXrCIKw2EXXumqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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