SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cc5ffe61be7550a592503f7db7d3d0e7ed69cd70dcda903a446688579c18913' 
  AND token = 'W38YVk2xhAzLtazFLFXy+lmMrMd26C56rR/8/5lTjBI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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