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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e574a1c56ff7c3dc20cc5e942ee36ac71b2576b55aa6a7e0ee18edd35edd6db8' 
  AND token = 'vzWYvOKQh26+lEJDC7uT9ujGHWzKcimMOak3VDtlaoA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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