SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12bba70e36ce5991cb2d443a35245668cbabe361b14e04b2aa366916c7d1ec49' 
  AND token = 'nWOvPgFs8JdULV9+cUsOHf8qzPcKsrHl43/9SczYVtk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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