SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84c7268a3c7e04064f9fdacffe7d93c5437e63045c27eee667d6893e8a266f3e' 
  AND token = 'G17tvb6FOMxGBC9UCQFSEbzVBOPu72tTfzSySfVIevs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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