SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe55b187053388254ea7913bcf69d01c721e18f1233f0d566ec42b0ae50c8a92' 
  AND token = 'FBvKLpAE+QY/mKfjYU3ZCG+A5j6gJlp4j+m3RAXohr8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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