SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '566250f8d1918132ea7cb6740bc38aa4527186e5121beef02a9e57d1be3a6f7e' 
  AND token = 'VDPt5NiGgpw6MS8IfAcvRgfnHXIL9UU3K5gwTLnv98Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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