SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c92f922e3a2b1128e17c56a5dbaedc2f3d89e4c00403db9ac5fec570a175a7bc' 
  AND token = 'DhB8GyDGeAjBXJc/oGRjedzBrnUNXhuMdDL61829gbw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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