SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4de15f45a4b7314519903dd2f26beebad0c68a1aa9256e573cd875f8224e6d9' 
  AND token = 'c8BMv7/Xea+yAPhxq2pXU2gGHSgUgjSabdu8NQt2t84=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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