SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '066b66ef8d9587445097719402973a04def1c4825a7d873b3ee37ba044e319a7' 
  AND token = 'EBc/PIjmrZD1sJnIGyk9bSRUO8gsPCqM3rojIXiNq1s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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