SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'adb89802c0d078f239ea69bafe473321001bb6e794d40316f93e4be20da7252e' 
  AND token = 'b8hgZdWmDz7ybEnYMyALCvf7OEhfWRRLvOL6lrCOD1I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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