SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29b655c1ee2180df0c000941f2373513c5755aa50f3fc91a6c435b876da5c2f2' 
  AND token = '2SVeFLem7+ns/rjIACBbPX2qZ+LGaStJTJvkpiygP1s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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