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SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '526b6ad98b1a0966a3599117b5dcf4ba352a3f477a380a8d6ac2095aa9c8bc7f' 
  AND token = 'cuzCl8dryd8QH8ihvtDHVp+AExakDUUdejWHHLF28BA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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