SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8159c9cd6a9b63dbc4297dcaa2f5c344b95f024e9c5d45ac576bd3338ec9ee6' 
  AND token = 'mQuZwVFWgF2PQiOJlQqXBGzzQMlUEUTnX81/PEdWMnM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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