SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a3abcc979a1e1d8af682245954077bfc04fe7759e8039bfb6a331220e01f494' 
  AND token = 'K6BZOfLYG1BG/UKhjhgAGFWq9sgSnvS1sYEBi2qk81U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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