SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75b1594e89851e0e941ffa958e2033d4d160a0c56c03bbf92e8c5e5b3906d7fd' 
  AND token = 'UOSRFXpmV0WSIKNxdjxw4fQR/94xy5747xSZst0yRIo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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