SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2877d57a152806be47e8af2fccd809f029da994637df6feffd17067b16ac8dba' 
  AND token = 'q4qLbmr67mWs2L5o2gNZecBEInA2ipQFZXcRHbeQv2c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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