SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a67d66ec3351a057d3c13e39225619d997edb6c6e60b57ffe3b88d14651fd673' 
  AND token = 'u7UIy2u7JELuYsyYZcb/l0dTIaTZspTjuaVp82EiGQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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