SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38f96b0e08487c5d7fc30b92d0b7dd69ad791c4aea0d716d9563f5d5bf43fcd2' 
  AND token = 'GRgMlCPRDRSeZMCrnYpaTYOnCYwVtdifDvpiZdxJ378=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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