SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4610e2126fa4cc388682576a0a288656427bc2e1906a4d05fc77d014860b98f2' 
  AND token = 'f/OMlTld7EmLyF2Incl4hyldkP34Asc9qWmSIyeboow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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