SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c31635855ee2cde62bf4479c04e6e9e12dfb92f416d01057d8e7fb83ce45d4f0' 
  AND token = 'sQmvMniVKpRoLIqpjm14aMiCyZ+8zDS+qDrdEfqul2M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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