SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2dde0f6b37b09dc7294fc3c6b0ad79e29044cd9c21ddc2c23c0051c653f4a7fe' 
  AND token = 'zKCtmgTOKLNYUl/Zhvg6pGu6LmBJZpHrrEgCIAv/nXI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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