SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5706d1f1cb298060a98f58e68ad292a95b12a29834cc6754071c9ff34ce67f5' 
  AND token = 'a2V+ir22jtZ8HG0FjFWzuqhYNj0W8PMEaqxetcMv3Uw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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