SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd57e2c020e7991af74c1038207e0e405560e52324ff73090df37465ffb8b11c4' 
  AND token = 'kgV+2tHyGx8C1DYqPKnztrfyJqDLlzm2f+yFzhFEHic=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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