SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '021873f9755f7f10179fb4e0f2d052f56cde82665355089d85d3ac631d50fe27' 
  AND token = 'Oc2rD1/eDs4iKd+sB26rCnD+YamG6LE+85zdNXH2YtI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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