SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53e7f9b8da445ef2def2d2003219330c7f04aa7dfc9d327930611f244b1f927c' 
  AND token = 'OMRl+GiB+iu+/FkjGRJtFwCqIA35d6pGF7lAeo5D4UI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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