SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68d889ad00d466bb1747fcadd8a9b2540dcc131d6e252e6d6905549091495f91' 
  AND token = 'tBkk9xPdtdYV7AvSNKPfpfr9Chtnv/nrXqwiXvlA5iI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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