SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '64d3f284e53cbb27f18d728fed248072900e9376f6123dee48c4612f496f4f27' 
  AND token = 'pygFxkqTNrAEjj6J+4Ms33Bkk3GgrtBcUpG+PjSBECo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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