SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73b3f5dbe0728b5dcf19966f5181489fa6b38fbc494dcd83d1c9dc637bedacce' 
  AND token = 'WVXN+KT4D5ijtP3jn1+bvnHAHvs4hq+VjMn9hCQqz88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}