SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3df6f7ae3f74bf2d9b310095f3983392d208ccf86da0468bf09189e107fdf27' 
  AND token = 'XqnSkRw0brqifINPc3oiwW+gmY0kyt3NDrzt9amy1yY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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