SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08c1ddc0af5e5efdc437a8d0276aff69407e1b6f08366a401aabbcbd1c3da8f3' 
  AND token = '0+gCJmGHqFkglRHjXgSyVGLyk2J35JhPHqN571+Ygek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}