SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c4d37bde56bd3b2e79bd979ea379a2836b666a48320b83c5d3d7bf4db9144c6' 
  AND token = 'sBMMxYI4HgC3NSNn4JkiCHIIbzwuh0gOOUYLHNL1sfA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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