SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '562f0b2f64beae231257f6b13dee8b34c876df427c03460c56c14860592af908' 
  AND token = 'vpQBjLyaXxL2Z5PP+y7IvnyojJQM46s8UBYADoWnLCg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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