SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '639788be5b87272e17056c94a09006fffd26bef34498bdfe3fab15fc8b5c155d' 
  AND token = 'LPMICie6PZD8cMCwlGmgxizw9pegI4GOx8a38QD8YJc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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