SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfe610e644fde03df2bc55217e642d81e75376910425d02a45266c503d00cefd' 
  AND token = '3fvE6bS3PpdHAXUrlD6VskLp0Hv68oDE41MJbp05HXE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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