SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03cf38fad054aab5177ab7d57096abee246fb89cc019f0c74c8b0e16a59391e9' 
  AND token = '0buie+5of84eyzfz84fsISiKZCo35si7cWi4tyZjvng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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