SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb4778ea6a7a3fd58df4d8122fdb10e2c3390984d155183a2aa3e1f9c0c21f2c' 
  AND token = 'ToB2+ooK5XNTjqjL1c/uiLQTCgYHaW9JVzu53msDm4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00073

JSON explain

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