SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76cdba765194e38b4e3f82a2af8757c1c4e73efa6f472a289d54389131b9f18e' 
  AND token = '/N8flj+R/ibrILDuzV3XCJBcNyKPbPOCars+LQroVzo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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