SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f70783af24ed970c11ae634e0502cc449888585b2be3635c3106d1f81ae4d99' 
  AND token = 'LMJ9Yv/L0ol76V1tVmxETIIHo1Pc3ZjBWIuT2YPnAIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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