SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd236c897e1b306f514b68e67ef5b49b3e8fdb04258be60163ee854904e158796' 
  AND token = 'z1x+WSJPRuEe8vgfVUrOKtTKkBQqAWZjoPSlCSzE3VY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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